Why wont the piston not go down far enough to let gas in on my 40 cc 2 stroke engine?

alright so on the 40 cc 2 stroke engine the piston will not go down far enough to let gas in. i took a video so yall could see what i mean.
as you can see it will go up and down but wont go any lower than the top of the intake manifold. i stuck my finger in ther and try to move it around and its not loose or wobbly or anything. any advice?

oh and i know for sure the engine runs good because i just got it running with the carb off and dumping gas strait into the cylinder through the spark plug hole.

and it sounded pretty good to

i want to say its supposed to do that but then how would it suck gas in through the carburater

yea u are right. i found out today that its not supposed to go down that far. it sucks gas underneath the piston then blows it through a tube to the top then fires.

but i still have a problem lol. it still wont start without pourin gas directly in the spark plug hole. so i guess its a carb problem but the carb is spotless

check all your gaskets and it it has a needle valve clean that and make sure nothings blocking it.